This invention pertains to a few methods for forming a high temperature and shock resistant insulated pipe, particularly large diameter pipes carrying high temperature gases and/or fluidized solids.
An exemplary pipe is a fluid catalytic cracking unit (FCCU) regenerator flue gas line for carrying gases at temperatures generally in the range of 1,000.degree. F. to 1,500.degree. F. (538.degree. C.-816.degree. C.) and pressures in the range of 1 to 4 atmospheres, absolute (1.033Kg/cm.sup.2 -4.133 Kg/cm.sup.2).
Various methods of forming various insulated pipes have been used, but the problems of providing a minimum of expansion in the pipe by having very good internal insulation and having the internal insulation strong enough to withstand stress due to pressure variations and solids flowing at high velocities therein are difficult to solve. Another problem to solve or purpose is to obviate high alloy construction where temperatures exceed those for which allowable stress values are set for carbon steel and low alloy steels, which steels are desired to be used in pipes. Two types of insulation for pipes have been used but they fail to withstand flowing conditions and/or stresses encounterest in service.